1. Field of the invention
The present invention relates to a process for preparing a nickel layer by chemical plating.
2. Description of the Prior arts
Glass plates having each thin transparent or translucent metal layer made of silver, nickel or aluminum which reflect or intercept heat radiation of solar or radiant heat have been known as heat radiation reflecting glass plates and have been used as a single glass plate, a double layer glass plate or a laminated glass plate in buildings, vehicles and various apparatuses and instruments. Among these metal coated glass plates, the glass plate having a nickel layer has superior heat radiation reflectivity and superior durability to the glass plates having the other metal layer and has a transparent neutral grey color and accordingly, it is one of excellent heat radiation reflecting glass. The nickel layer of said glass plate is usually formed by a vacuum evaporation process, a sputtering process, or a chemical plating process. Among them, the chemical plating process for applying a nickel salt and a reducing agent on a glass plate and reducing said nickel salt by a chemical reaction to form a nickel layer on the glass plate has various advantages that the nickel layer can be formed at an ambient temperature, and it can be formed for a short time in high productivity and it can be easily formed without using an expensive apparatus as required in the vacuum evaporation process or the sputtering process. The chemical plating process, however, has disadvantages that a rate of deposition is not easily controlled and a nickel layer having a desired thickness or uniform thickness is not easily formed and color unevenness is caused, and pinholes are caused and a uniform dense layer is not easily formed.